why are the edges of uv unwrap blurred? and how to fix
The blurred part in your image is create around the outside of boundary of each UV island when you bake. It is called the margin, and is used to hide/minimise various texture sampling errors that can occur around seams in some renderers.

You can control the size using the margin setting in the bake settings panel under output (in your screenshot it is set to 16px).

You may need to reduce this value if your image is low res or your islands are very close together to avoid overlap.

You can also control how much space there is between your islands when you make your UV layout, see https://docs.blender.org/manual/en/latest/editors/uv_image/uv/editing/unwrapping/mapping_types.html